An old friend of mine "wore out" a .270 Winchester (Belgium Browning) in 700 rounds - 2" of smokey throat erosion ahead of the chamber and groups opened to 1 1/2" - 1/2" larger than his 'maximum' allowable grouping. I assume he must have shot it VERY hot & as well, he was also using 'old' Hodgdon 4831 data for his new IMR4831 powder. He was only having slightly sticky extraction and the brass didn't last well - 3 or 4 shots, but locals told him that was normal??? He was recording 3,100fps with 150 Sierra BT's, which happened to be his favourite moose bullet at that time. One shot through the lungs, dead moose - straight down. He is a good shot.

I re-barreled his Belgium Browning with a Pac-Nor 26" tube, got him straightened around on his loads and he's getting just over 2,900fps with the 150 Sierra's. He says it kills just as well as it did before, of course and it will put 5 into a sub 1" group at 200 meters with double bags.

Standard calibres do well with long barrels too.